Performing autonomous path navigation using deep neural networks

ABSTRACT

A method, computer readable medium, and system are disclosed for performing autonomous path navigation using deep neural networks. The method includes the steps of receiving image data at a deep neural network (DNN), determining, by the DNN, both an orientation of a vehicle with respect to a path and a lateral position of the vehicle with respect to the path, utilizing the image data, and controlling a location of the vehicle, utilizing the orientation of the vehicle with respect to the path and the lateral position of the vehicle with respect to the path.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/921,796 filed Jul. 6, 2020, entitled “PERFORMING AUTONOMOUS PATHNAVIGATION USING DEEP NEURAL NETWORKS,” which is a continuation of U.S.application Ser. No. 15/939,116, filed on Mar. 28, 2018, now U.S. Pat.No. 10,705,525, entitled “PERFORMING AUTONOMOUS PATH NAVIGATION USINGDEEP NEURAL NETWORKS,” which claims the benefit of U.S. ProvisionalApplication No. 62/483,155, filed on Apr. 7, 2017, entitled “LOW-FLYINGAUTONOMOUS DRONE TRAIL NAVIGATION USING DEEP NEURAL NETWORKS,” theentire contents of which are incorporated herein by reference.

This application also incorporates by reference for all purposes thefull disclosures of co-pending U.S. patent application Ser. No. ______,filed concurrently herewith, entitled “PERFORMING AUTONOMOUS PATHNAVIGATION USING DEEP NEURAL NETWORKS” (Attorney Docket No.0112912-021US2).”

FIELD OF THE INVENTION

The present invention relates to autonomous vehicle navigation, and moreparticularly to analyzing image data using deep neural networks in orderto produce vehicle navigation information.

BACKGROUND

Autonomous control is a desirable feature for implementation intovehicles. However, current control implementations are often inaccurateand inefficient, as well as unaware of an environment surrounding thevehicle.

Thus, there is a need for addressing these issues and/or other issuesassociated with the prior art.

SUMMARY

A method, computer readable medium, and system are disclosed forperforming autonomous path navigation using deep neural networks. Themethod includes the steps of receiving image data at a deep neuralnetwork (DNN), determining, by the DNN, both an orientation of a vehiclewith respect to a path and a lateral position of the vehicle withrespect to the path, utilizing the image data, and controlling alocation of the vehicle, utilizing the orientation of the vehicle withrespect to the path and the lateral position of the vehicle with respectto the path.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a flowchart of a method for performing autonomouspath navigation using deep neural networks, in accordance with oneembodiment.

FIG. 2 illustrates a parallel processing unit, in accordance with oneembodiment.

FIG. 3 illustrates a general processing cluster within the parallelprocessing unit of FIG. 2, in accordance with one embodiment.

FIG. 4 illustrates a memory partition unit of the parallel processingunit of FIG. 2, in accordance with one embodiment.

FIG. 5 illustrates the streaming multi-processor of FIG. 3, inaccordance with one embodiment.

FIG. 6 is a conceptual diagram of a processing system implemented usingthe PPU of FIG. 2, in accordance with one embodiment.

FIG. 7 illustrates an exemplary system in which the various architectureand/or functionality of the various previous embodiments may beimplemented.

FIG. 8 illustrates an exemplary system for performing autonomous pathnavigation using deep neural networks, in accordance with oneembodiment.

FIG. 9 illustrates an exemplary software architecture, in accordancewith one embodiment.

FIG. 10 illustrates an exemplary TrailNet DNN node implementing a deepneural network (DNN), in accordance with one embodiment.

DETAILED DESCRIPTION

FIG. 1 illustrates a flowchart of a method 100 for performing autonomouspath navigation using deep neural networks, in accordance with oneembodiment. As shown in operation 102, image data is received at a deepneural network (DNN). In one embodiment, the image data may include apictorial image. In another embodiment, the image data may include aplurality of pictorial images. In yet another embodiment, the image datamay be derived from video data (e.g., streaming video, etc.).

Additionally, in one embodiment, the image data may include opticaldata, infrared data, light detection and ranging (LIDAR) data, radardata, depth data, sonar data, etc. In another embodiment, the image datamay include stereo image data received from a plurality of imagingdevices. In yet another embodiment, the image data may be received fromone or more imaging devices. For example, the image data may be receivedfrom a digital imaging camera, a radar device, a LIDAR device, aninfrared imaging device, a sonar imaging device, etc.

Further, in one embodiment, the image data may be received in real-timefrom the one or more imaging devices. In another embodiment, the imagedata may be received from one or more hardware imaging devices,utilizing middleware (e.g., a robotic operating system (ROS), etc.). Inyet another embodiment, the image data may be received at a vehicle thatincludes the one or more imaging devices. For example, the vehicle mayinclude any controlled mobile object, such as an automobile, airplane,amphibious vehicle (e.g., a boat, hydroplane, etc.) drone, micro aerialvehicle (MAV), rover, etc. In another example, the middleware may berunning on hardware installed within the vehicle. In yet anotherexample, the one or more cameras may be installed within the vehicle.

Further still, in one embodiment, the image data may indicate a currentlocation of the vehicle on a path. For example, the one or more imagingdevices may be mounted on the vehicle such that the image data createdby the one or more imaging devices indicates the current location of thevehicle on the path. In another embodiment, the DNN may include asupervised classification network.

For example, the image data may include supervised data that iscorrectly labeled with an associated position. In another example, theDNN may be trained with image data having associated correct labels. Inanother embodiment, the DNN may implement a loss function. For example,the DNN may determine a label for the image data, compare the label tothe associated correct label for the image data, and may compute adifference between the labels. In another example, the DNN may beadjusted, based on the difference between the labels, using backpropagation.

In this way, the DNN may be more likely to correctly label image dataduring subsequent iterations.

Also, as shown in operation 104, the DNN determines both an orientationof a vehicle with respect to a path and a lateral position of thevehicle with respect to the path, utilizing the image data. In oneembodiment, the path may include any course that may be identifiedvisually within the image data. In another embodiment, the path mayinclude a trail, one or more tracks (e.g., train tracks, tire tracks,etc.), one or more power lines, a street, a culvert (e.g., a sewerculvert, etc.), an urban canyon, etc.

In addition, in one embodiment, the vehicle may include the vehiclerunning middleware and the one or more imaging devices. In anotherembodiment, the vehicle may currently be in motion (e.g., along thepath, etc.). In yet another embodiment, the orientation with respect tothe path may include a plurality of probabilities. For example, theorientation with respect to the path may include a probability that avehicle is currently facing left with respect to the path, a probabilitythat a vehicle is currently facing right with respect to the path, and aprobability that a vehicle is currently facing straight with respect tothe path. In another example, each of the plurality of possibilities maybe represented numerically, resulting in three numbers output by the DNNthat indicate the orientation with respect to the path.

Furthermore, in one embodiment, the lateral position with respect to thepath may include a plurality of probabilities. In another embodiment,the lateral position with respect to the path may identify a probabilityof a plurality of lateral offsets with respect to the path center. Forexample, the lateral position with respect to the path may include aprobability that a vehicle is currently shifted left with respect to thepath, a probability that a vehicle is currently shifted right withrespect to the path, and a probability that a vehicle is centered withrespect to the path. In another example, each of the plurality ofpossibilities may be represented numerically, resulting in three numbersoutput by the DNN that indicate the lateral position with respect to thepath.

Further still, in one embodiment, the orientation and lateral positionmay be determined in real-time within the vehicle. In anotherembodiment, the image data may be sent from the vehicle to a remotelocation (e.g., a distributed computing environment), and theorientation and lateral position may be determined at the remotelocation.

In this way, both rotation and translation data may be determined by theDNN, utilizing the image data.

Also, as shown in operation 106, a location of the vehicle iscontrolled, utilizing the orientation of the vehicle with respect to thepath and the lateral position of the vehicle with respect to the path.In one embodiment, the orientation of the vehicle with respect to thepath and the lateral position of the vehicle with respect to the pathmay be converted into steering directions. For example, the conversionmay be performed by a controller module. In another example, thesteering directions may include one or more steering signals (e.g., asteering angle, etc.).

Additionally, in one embodiment, the steering directions may beconverted into another protocol to create converted steering directions.For example, the steering directions may be converted from a middlewareprotocol (e.g., a ROS protocol, etc.) to a vehicle control protocol. Inanother example, the conversion may be performed by a communicationmodule.

Furthermore, in one embodiment, the converted steering directions may besent to a vehicle systems module to control one or more steeringmechanisms of the vehicle. For example, the one or more steeringmechanisms of the vehicle may control a direction in which the vehicleis moving. In another example, the converted steering directions may besent to the vehicle systems module utilizing a communication protocol.

Further still, in one embodiment, the one or more steering mechanismsmay be adjusted, based on the converted steering directions. Forexample, the one or more steering mechanisms may be adjusted by thevehicle systems module to move the vehicle laterally to the center ofthe path. In another example, the one or more steering mechanisms may beadjusted to move the vehicle so that the orientation of the vehicle isstraight with respect to the path. In another embodiment, the vehiclelocation controlling may be performed in real-time within the vehicle.

Also, in one embodiment, the DNN may control directional stability byutilizing predictions with a reduced confidence. For example, the DNNmay implement a classification scheme with a reduced confidence for moresmooth and stable vehicle direction control.

In addition, in one embodiment, a second DNN may perform objectdetection within the path. For example, the second DNN may be includedwithin the vehicle and may communicate to other modules within thevehicles (e.g., via middleware, etc.). In another example, the secondDNN may receive the image data, and may output object data indicatingwhether an object (e.g., a person, animal, etc.) is in the image data.In yet another example, the object data may be sent from the second DNNto the controller module (e.g., via middleware, etc.). In still anotherexample, the controller module may determine whether a size of theobject in the image data is a predetermined percentage of a size of theimage in the image data.

Further, in one example, the controller module may send one or morecommands to the vehicle systems (e.g., to change a course of thevehicle, to stop a functioning of the vehicle, etc.) in response todetermining that the size of the object in the image data is equal to orgreater than the predetermined percentage of the size of the image inthe image data. This may provide a safety mechanism that may stop thevehicle when an object of a predetermined size is on the path.

Further still, in one embodiment, a third DNN may perform obstacledetection associated with the path. For example, the third DNN may beincluded within the vehicle and may communicate to other modules withinthe vehicles (e.g., via middleware, etc.). In another example, the thirdDNN may receive the image data, and may output obstacle data such as aset of weights indicating a likelihood of one or more obstacles atvarious locations and distances along the path. For instance, the thirdDNN may implement simultaneous localization and mapping (SLAM) toidentify a location of the vehicle within a scene indicated by the imagedata and provide information about a relative location of static objectswithin the scene.

Also, in one example, the obstacle data may be sent from the third DNNto the controller module (e.g., via middleware, etc.). In anotherexample, the controller module may adjust the location of the vehicle,utilizing the obstacle data. This may help the vehicle avoid staticobstacles in an alongside the path.

In this way, a vehicle may be autonomously controlled, utilizingsteering directions derived from DNN analysis of image data.Additionally, a DNN may perform an estimation of both vehicleorientation (3 classes) and lateral position with respect to path (3more classes), for a total of 6 classes. Further, a loss function may beimplemented during specific DNN training. Further still, a reducedconfidence implementation may be performed within a DNN. Also, objectand obstacle detection may be performed during autonomous navigation viaadditional DNNs. In addition, these features may be implementedutilizing on-board, real-time processing.

Parallel Processing Architecture

FIG. 2 illustrates a parallel processing unit (PPU) 300, in accordancewith one embodiment. In one embodiment, the PPU 300 is a multi-threadedprocessor that is implemented on one or more integrated circuit devices.The PPU 300 is a latency hiding architecture designed to process manythreads in parallel. A thread (i.e., a thread of execution) is aninstantiation of a set of instructions configured to be executed by thePPU 300. In one embodiment, the PPU 300 is a graphics processing unit(GPU) configured to implement a graphics rendering pipeline forprocessing three-dimensional (3D) graphics data in order to generatetwo-dimensional (2D) image data for display on a display device such asa liquid crystal display (LCD) device. In other embodiments, the PPU 300may be utilized for performing general-purpose computations. While oneexemplary parallel processor is provided herein for illustrativepurposes, it should be strongly noted that such processor is set forthfor illustrative purposes only, and that any processor may be employedto supplement and/or substitute for the same.

One or more PPUs 300 may be configured to accelerate thousands of HighPerformance Computing (HPC), data center, and machine learningapplications. The PPU 300 may be configured to accelerate numerous deeplearning systems and applications including autonomous vehicleplatforms, deep learning, high-accuracy speech, image, and textrecognition systems, intelligent video analytics, molecular simulations,drug discovery, disease diagnosis, weather forecasting, big dataanalytics, astronomy, molecular dynamics simulation, financial modeling,robotics, factory automation, real-time language translation, onlinesearch optimizations, and personalized user recommendations, and thelike.

As shown in FIG. 2, the PPU 300 includes an Input/Output (I/O) unit 305,a front end unit 315, a scheduler unit 320, a work distribution unit325, a hub 330, a crossbar (Xbar) 370, one or more general processingclusters (GPCs) 350, and one or more partition units 380. The PPU 300may be connected to a host processor or other PPUs 300 via one or morehigh-speed NVLink 310 interconnect. The PPU 300 may be connected to ahost processor or other peripheral devices via an interconnect 302. ThePPU 300 may also be connected to a local memory comprising a number ofmemory devices 304. In one embodiment, the local memory may comprise anumber of dynamic random access memory (DRAM) devices. The DRAM devicesmay be configured as a high-bandwidth memory (HBM) subsystem, withmultiple DRAM dies stacked within each device.

The NVLink 310 interconnect enables systems to scale and include one ormore PPUs 300 combined with one or more CPUs, supports cache coherencebetween the PPUs 300 and CPUs, and CPU mastering. Data and/or commandsmay be transmitted by the NVLink 310 through the hub 330 to/from otherunits of the PPU 300 such as one or more copy engines, a video encoder,a video decoder, a power management unit, etc. (not explicitly shown).The NVLink 310 is described in more detail in conjunction with FIG. 5.

The I/O unit 305 is configured to transmit and receive communications(i.e., commands, data, etc.) from a host processor (not shown) over theinterconnect 302. The I/O unit 305 may communicate with the hostprocessor directly via the interconnect 302 or through one or moreintermediate devices such as a memory bridge. In one embodiment, the I/Ounit 305 may communicate with one or more other processors, such as oneor more the PPUs 300 via the interconnect 302. In one embodiment, theI/O unit 305 implements a Peripheral Component Interconnect Express(PCIe) interface for communications over a PCIe bus and the interconnect302 is a PCIe bus. In alternative embodiments, the I/O unit 305 mayimplement other types of well-known interfaces for communicating withexternal devices.

The I/O unit 305 decodes packets received via the interconnect 302. Inone embodiment, the packets represent commands configured to cause thePPU 300 to perform various operations. The I/O unit 305 transmits thedecoded commands to various other units of the PPU 300 as the commandsmay specify. For example, some commands may be transmitted to the frontend unit 315. Other commands may be transmitted to the hub 330 or otherunits of the PPU 300 such as one or more copy engines, a video encoder,a video decoder, a power management unit, etc. (not explicitly shown).In other words, the I/O unit 305 is configured to route communicationsbetween and among the various logical units of the PPU 300.

In one embodiment, a program executed by the host processor encodes acommand stream in a buffer that provides workloads to the PPU 300 forprocessing. A workload may comprise several instructions and data to beprocessed by those instructions. The buffer is a region in a memory thatis accessible (i.e., read/write) by both the host processor and the PPU300. For example, the host interface unit 310 may be configured toaccess the buffer in a system memory connected to the interconnect 302via memory requests transmitted over the interconnect 302 by the I/Ounit 305. In one embodiment, the host processor writes the commandstream to the buffer and then transmits a pointer to the start of thecommand stream to the PPU 300. The front end unit 315 receives pointersto one or more command streams. The front end unit 315 manages the oneor more streams, reading commands from the streams and forwardingcommands to the various units of the PPU 300.

The front end unit 315 is coupled to a scheduler unit 320 thatconfigures the various GPCs 350 to process tasks defined by the one ormore streams. The scheduler unit 320 is configured to track stateinformation related to the various tasks managed by the scheduler unit320. The state may indicate which GPC 350 a task is assigned to, whetherthe task is active or inactive, a priority level associated with thetask, and so forth. The scheduler unit 320 manages the execution of aplurality of tasks on the one or more GPCs 350.

The scheduler unit 320 is coupled to a work distribution unit 325 thatis configured to dispatch tasks for execution on the GPCs 350. The workdistribution unit 325 may track a number of scheduled tasks receivedfrom the scheduler unit 320. In one embodiment, the work distributionunit 325 manages a pending task pool and an active task pool for each ofthe GPCs 350. The pending task pool may comprise a number of slots(e.g., 32 slots) that contain tasks assigned to be processed by aparticular GPC 350. The active task pool may comprise a number of slots(e.g., 4 slots) for tasks that are actively being processed by the GPCs350. As a GPC 350 finishes the execution of a task, that task is evictedfrom the active task pool for the GPC 350 and one of the other tasksfrom the pending task pool is selected and scheduled for execution onthe GPC 350. If an active task has been idle on the GPC 350, such aswhile waiting for a data dependency to be resolved, then the active taskmay be evicted from the GPC 350 and returned to the pending task poolwhile another task in the pending task pool is selected and scheduledfor execution on the GPC 350.

The work distribution unit 325 communicates with the one or more GPCs350 via XBar 370. The XBar 370 is an interconnect network that couplesmany of the units of the PPU 300 to other units of the PPU 300. Forexample, the XBar 370 may be configured to couple the work distributionunit 325 to a particular GPC 350. Although not shown explicitly, one ormore other units of the PPU 300 may also be connected to the XBar 370via the hub 330.

The tasks are managed by the scheduler unit 320 and dispatched to a GPC350 by the work distribution unit 325. The GPC 350 is configured toprocess the task and generate results. The results may be consumed byother tasks within the GPC 350, routed to a different GPC 350 via theXBar 370, or stored in the memory 304. The results can be written to thememory 304 via the partition units 380, which implement a memoryinterface for reading and writing data to/from the memory 304. Theresults can be transmitted to another PPU 304 or CPU via the NVLink 310.In one embodiment, the PPU 300 includes a number U of partition units380 that is equal to the number of separate and distinct memory devices304 coupled to the PPU 300. A partition unit 380 will be described inmore detail below in conjunction with FIG. 4.

In one embodiment, a host processor executes a driver kernel thatimplements an application programming interface (API) that enables oneor more applications executing on the host processor to scheduleoperations for execution on the PPU 300. In one embodiment, multiplecompute applications are simultaneously executed by the PPU 300 and thePPU 300 provides isolation, quality of service (QoS), and independentaddress spaces for the multiple compute applications. An application maygenerate instructions (i.e., API calls) that cause the driver kernel togenerate one or more tasks for execution by the PPU 300. The driverkernel outputs tasks to one or more streams being processed by the PPU300. Each task may comprise one or more groups of related threads,referred to herein as a warp. In one embodiment, a warp comprises 32related threads that may be executed in parallel. Cooperating threadsmay refer to a plurality of threads including instructions to performthe task and that may exchange data through shared memory. Threads andcooperating threads are described in more detail in conjunction withFIG. 5.

FIG. 3 illustrates a GPC 350 of the PPU 300 of FIG. 2, in accordancewith one embodiment. As shown in FIG. 3, each GPC 350 includes a numberof hardware units for processing tasks. In one embodiment, each GPC 350includes a pipeline manager 410, a pre-raster operations unit (PROP)415, a raster engine 425, a work distribution crossbar (WDX) 480, amemory management unit (MMU) 490, and one or more Data ProcessingClusters (DPCs) 420. It will be appreciated that the GPC 350 of FIG. 3may include other hardware units in lieu of or in addition to the unitsshown in FIG. 3.

In one embodiment, the operation of the GPC 350 is controlled by thepipeline manager 410. The pipeline manager 410 manages the configurationof the one or more DPCs 420 for processing tasks allocated to the GPC350. In one embodiment, the pipeline manager 410 may configure at leastone of the one or more DPCs 420 to implement at least a portion of agraphics rendering pipeline. For example, a DPC 420 may be configured toexecute a vertex shader program on the programmable streamingmultiprocessor (SM) 440. The pipeline manager 410 may also be configuredto route packets received from the work distribution unit 325 to theappropriate logical units within the GPC 350. For example, some packetsmay be routed to fixed function hardware units in the PROP 415 and/orraster engine 425 while other packets may be routed to the DPCs 420 forprocessing by the primitive engine 435 or the SM 440. In one embodiment,the pipeline manager 410 may configure at least one of the one or moreDPCs 420 to implement a neural network model and/or a computingpipeline.

The PROP unit 415 is configured to route data generated by the rasterengine 425 and the DPCs 420 to a Raster Operations (ROP) unit in thepartition unit 380, described in more detail in conjunction with FIG. 4.The PROP unit 415 may also be configured to perform optimizations forcolor blending, organize pixel data, perform address translations, andthe like.

The raster engine 425 includes a number of fixed function hardware unitsconfigured to perform various raster operations. In one embodiment, theraster engine 425 includes a setup engine, a coarse raster engine, aculling engine, a clipping engine, a fine raster engine, and a tilecoalescing engine. The setup engine receives transformed vertices andgenerates plane equations associated with the geometric primitivedefined by the vertices. The plane equations are transmitted to thecoarse raster engine to generate coverage information (e.g., an x,ycoverage mask for a tile) for the primitive. The output of the coarseraster engine is transmitted to the culling engine where fragmentsassociated with the primitive that fail a z-test are culled, andtransmitted to a clipping engine where fragments lying outside a viewingfrustum are clipped. Those fragments that survive clipping and cullingmay be passed to the fine raster engine to generate attributes for thepixel fragments based on the plane equations generated by the setupengine. The output of the raster engine 425 comprises fragments to beprocessed, for example, by a fragment shader implemented within a DPC420.

Each DPC 420 included in the GPC 350 includes an M-Pipe Controller (MPC)430, a primitive engine 435, and one or more SMs 440. The MPC 430controls the operation of the DPC 420, routing packets received from thepipeline manager 410 to the appropriate units in the DPC 420. Forexample, packets associated with a vertex may be routed to the primitiveengine 435, which is configured to fetch vertex attributes associatedwith the vertex from the memory 304. In contrast, packets associatedwith a shader program may be transmitted to the SM 440.

The SM 440 comprises a programmable streaming processor that isconfigured to process tasks represented by a number of threads. Each SM440 is multi-threaded and configured to execute a plurality of threads(e.g., 32 threads) from a particular group of threads concurrently. Inone embodiment, the SM 440 implements a SIMD (Single-Instruction,Multiple-Data) architecture where each thread in a group of threads(i.e., a warp) is configured to process a different set of data based onthe same set of instructions. All threads in the group of threadsexecute the same instructions. In another embodiment, the SM 440implements a SIMT (Single-Instruction, Multiple Thread) architecturewhere each thread in a group of threads is configured to process adifferent set of data based on the same set of instructions, but whereindividual threads in the group of threads are allowed to diverge duringexecution. In one embodiment, a program counter, call stack, andexecution state is maintained for each warp, enabling concurrencybetween warps and serial execution within warps when threads within thewarp diverge. In another embodiment, a program counter, call stack, andexecution state is maintained for each individual thread, enabling equalconcurrency between all threads, within and between warps. Whenexecution state is maintained for each individual thread, threadsexecuting the same instructions may be converged and executed inparallel for maximum efficiency. The SM 440 will be described in moredetail below in conjunction with FIG. 5.

The MMU 490 provides an interface between the GPC 350 and the partitionunit 380. The MMU 490 may provide translation of virtual addresses intophysical addresses, memory protection, and arbitration of memoryrequests. In one embodiment, the MMU 490 provides one or moretranslation lookaside buffers (TLBs) for performing translation ofvirtual addresses into physical addresses in the memory 304.

FIG. 4 illustrates a memory partition unit 380 of the PPU 300 of FIG. 2,in accordance with one embodiment. As shown in FIG. 4, the memorypartition unit 380 includes a Raster Operations (ROP) unit 450, a leveltwo (L2) cache 460, and a memory interface 470. The memory interface 470is coupled to the memory 304. Memory interface 470 may implement 32, 64,128, 1024-bit data buses, or the like, for high-speed data transfer. Inone embodiment, the PPU 300 incorporates U memory interfaces 470, onememory interface 470 per pair of partition units 380, where each pair ofpartition units 380 is connected to a corresponding memory device 304.For example, PPU 300 may be connected to up to Y memory devices 304,such as high bandwidth memory stacks or graphics double-data-rate,version 5, synchronous dynamic random access memory (GDDR5 SDRAM).

In one embodiment, the memory interface 470 implements an HBM2 memoryinterface and Y equals half U. In one embodiment, the HBM2 memory stacksare located on the same physical package as the PPU 300, providingsubstantial power and area savings compared with conventional GDDR5SDRAM systems. In one embodiment, each HBM2 stack includes four memorydies and Y equals 4, with HBM2 stack including two 128-bit channels perdie for a total of 8 channels and a data bus width of 1024 bits.

In one embodiment, the memory 304 supports Single-Error CorrectingDouble-Error Detecting (SECDED) Error Correction Code (ECC) to protectdata. ECC provides higher reliability for compute applications that aresensitive to data corruption. Reliability is especially important inlarge-scale cluster computing environments where PPUs 300 process verylarge datasets and/or run applications for extended periods.

In one embodiment, the PPU 300 implements a multi-level memoryhierarchy. In one embodiment, the memory partition unit 380 supports aunified memory to provide a single unified virtual address space for CPUand PPU 300 memory, enabling data sharing between virtual memorysystems. In one embodiment the frequency of accesses by a PPU 300 tomemory located on other processors is traced to ensure that memory pagesare moved to the physical memory of the PPU 300 that is accessing thepages more frequently. In one embodiment, the NVLink 310 supportsaddress translation services allowing the PPU 300 to directly access aCPU's page tables and providing full access to CPU memory by the PPU300.

In one embodiment, copy engines transfer data between multiple PPUs 300or between PPUs 300 and CPUs. The copy engines can generate page faultsfor addresses that are not mapped into the page tables. The memorypartition unit 380 can then service the page faults, mapping theaddresses into the page table, after which the copy engine can performthe transfer. In a conventional system, memory is pinned (i.e.,non-pageable) for multiple copy engine operations between multipleprocessors, substantially reducing the available memory. With hardwarepage faulting, addresses can be passed to the copy engines withoutworrying if the memory pages are resident, and the copy process istransparent.

Data from the memory 304 or other system memory may be fetched by thememory partition unit 380 and stored in the L2 cache 460, which islocated on-chip and is shared between the various GPCs 350. As shown,each memory partition unit 380 includes a portion of the L2 cache 460associated with a corresponding memory device 304. Lower level cachesmay then be implemented in various units within the GPCs 350. Forexample, each of the SMs 440 may implement a level one (L1) cache. TheL1 cache is private memory that is dedicated to a particular SM 440.Data from the L2 cache 460 may be fetched and stored in each of the L1caches for processing in the functional units of the SMs 440. The L2cache 460 is coupled to the memory interface 470 and the XBar 370.

The ROP unit 450 performs graphics raster operations related to pixelcolor, such as color compression, pixel blending, and the like. The ROPunit 450 also implements depth testing in conjunction with the rasterengine 425, receiving a depth for a sample location associated with apixel fragment from the culling engine of the raster engine 425. Thedepth is tested against a corresponding depth in a depth buffer for asample location associated with the fragment. If the fragment passes thedepth test for the sample location, then the ROP unit 450 updates thedepth buffer and transmits a result of the depth test to the rasterengine 425. It will be appreciated that the number of partition units380 may be different than the number of GPCs 350 and, therefore, eachROP unit 450 may be coupled to each of the GPCs 350. The ROP unit 450tracks packets received from the different GPCs 350 and determines whichGPC 350 that a result generated by the ROP unit 450 is routed to throughthe Xbar 370.

FIG. 5 illustrates the streaming multi-processor 440 of FIG. 3, inaccordance with one embodiment. As shown in FIG. 5, the SM 440 includesan instruction cache 505, one or more scheduler units 511, a registerfile 520, one or more processing cores 550, one or more special functionunits (SFUs) 552, one or more load/store units (LSUs) 554, aninterconnect network 580, a shared memory/L1 cache 570.

As described above, the work distribution unit 325 dispatches tasks forexecution on the GPCs 350 of the PPU 300. The tasks are allocated to aparticular DPC 420 within a GPC 350 and, if the task is associated witha shader program, the task may be allocated to an SM 440. The schedulerunit 511 receives the tasks from the work distribution unit 325 andmanages instruction scheduling for one or more thread blocks assigned tothe SM 440. The scheduler unit 511 schedules thread blocks for executionas warps of parallel threads, where each thread block is allocated atleast one warp. In one embodiment, each warp executes 32 threads. Thescheduler unit 511 may manage a plurality of different thread blocks,allocating the warps to the different thread blocks and then dispatchinginstructions from the plurality of different cooperative groups to thevarious functional units (i.e., cores 550, SFUs 552, and LSUs 554)during each clock cycle.

Cooperative Groups is a programming model for organizing groups ofcommunicating threads that allows developers to express the granularityat which threads are communicating, enabling the expression of richer,more efficient parallel decompositions. Cooperative launch APIs supportsynchronization amongst thread blocks for the execution of parallelalgorithms. Conventional programming models provide a single, simpleconstruct for synchronizing cooperating threads: a barrier across allthreads of a thread block (i.e., the syncthreads( ) function). However,programmers would often like to define groups of threads at smaller thanthread block granularities and synchronize within the defined groups toenable greater performance, design flexibility, and software reuse inthe form of collective group-wide function interfaces.

Cooperative Groups enables programmers to define groups of threadsexplicitly at sub-block (i.e., as small as a single thread) andmulti-block granularities, and to perform collective operations such assynchronization on the threads in a cooperative group. The programmingmodel supports clean composition across software boundaries, so thatlibraries and utility functions can synchronize safely within theirlocal context without having to make assumptions about convergence.Cooperative Groups primitives enable new patterns of cooperativeparallelism, including producer-consumer parallelism, opportunisticparallelism, and global synchronization across an entire grid of threadblocks.

A dispatch unit 515 is configured to transmit instructions to one ormore of the functional units. In the embodiment, the scheduler unit 511includes two dispatch units 515 that enable two different instructionsfrom the same warp to be dispatched during each clock cycle. Inalternative embodiments, each scheduler unit 511 may include a singledispatch unit 515 or additional dispatch units 515.

Each SM 440 includes a register file 520 that provides a set ofregisters for the functional units of the SM 440. In one embodiment, theregister file 520 is divided between each of the functional units suchthat each functional unit is allocated a dedicated portion of theregister file 520. In another embodiment, the register file 520 isdivided between the different warps being executed by the SM 440. Theregister file 520 provides temporary storage for operands connected tothe data paths of the functional units.

Each SM 440 comprises L processing cores 550. In one embodiment, the SM440 includes a large number (e.g., 128, etc.) of distinct processingcores 550. Each core 550 may include a fully-pipelined,single-precision, double-precision, and/or mixed precision processingunit that includes a floating point arithmetic logic unit and an integerarithmetic logic unit. In one embodiment, the floating point arithmeticlogic units implement the IEEE 754-2008 standard for floating pointarithmetic. In one embodiment, the cores 550 include 64 single-precision(32-bit) floating point cores, 64 integer cores, 32 double-precision(64-bit) floating point cores, and 8 tensor cores.

Tensor cores configured to perform matrix operations, and, in oneembodiment, one or more tensor cores are included in the cores 550. Inparticular, the tensor cores are configured to perform deep learningmatrix arithmetic, such as convolution operations for neural networktraining and inferencing. In one embodiment, each tensor core operateson a 4×4 matrix and performs a matrix multiply and accumulate operationD=A×B+C, where A, B, C, and D, are 4×4 matrices.

In one embodiment, the matrix multiply inputs A and B are 16-bitfloating point matrices, while the accumulation matrices C and D may be16-bit floating point or 32-bit floating point matrices. Tensor Coresoperate on 16-bit floating point input data with 32-bit floating pointaccumulation. The 16-bit floating point multiply requires 64 operationsand results in a full precision product that is then accumulated using32-bit floating point addition with the other intermediate products fora 4×4×4 matrix multiply. In practice, Tensor Cores are used to performmuch larger two-dimensional or higher dimensional matrix operations,built up from these smaller elements. An API, such as CUDA 9 C++ API,exposes specialized matrix load, matrix multiply and accumulate, andmatrix store operations to efficiently use Tensor Cores from a CUDA-C++program. At the CUDA level, the warp-level interface assumes 16×16 sizematrices spanning all 32 threads of the warp.

Each SM 440 also comprises M SFUs 552 that perform special functions(e.g., attribute evaluation, reciprocal square root, and the like). Inone embodiment, the SFUs 552 may include a tree traversal unitconfigured to traverse a hierarchical tree data structure. In oneembodiment, the SFUs 552 may include texture unit configured to performtexture map filtering operations. In one embodiment, the texture unitsare configured to load texture maps (e.g., a 2D array of texels) fromthe memory 304 and sample the texture maps to produce sampled texturevalues for use in shader programs executed by the SM 440. In oneembodiment, the texture maps are stored in the shared memory/L1 cache470. The texture units implement texture operations such as filteringoperations using mip-maps (i.e., texture maps of varying levels ofdetail). In one embodiment, each SM 340 includes two texture units.

Each SM 440 also comprises N LSUs 554 that implement load and storeoperations between the shared memory/L1 cache 570 and the register file520. Each SM 440 includes an interconnect network 580 that connects eachof the functional units to the register file 520 and the LSU 554 to theregister file 520, shared memory/L1 cache 570. In one embodiment, theinterconnect network 580 is a crossbar that can be configured to connectany of the functional units to any of the registers in the register file520 and connect the LSUs 554 to the register file and memory locationsin shared memory/L1 cache 570.

The shared memory/L1 cache 570 is an array of on-chip memory that allowsfor data storage and communication between the SM 440 and the primitiveengine 435 and between threads in the SM 440. In one embodiment, theshared memory/L1 cache 570 comprises 128 KB of storage capacity and isin the path from the SM 440 to the partition unit 380. The sharedmemory/L1 cache 570 can be used to cache reads and writes. One or moreof the shared memory/L1 cache 570, L2 cache 460, and memory 304 arebacking stores.

Combining data cache and shared memory functionality into a singlememory block provides the best overall performance for both types ofmemory accesses. The capacity is usable as a cache by programs that donot use shared memory. For example, if shared memory is configured touse half of the capacity, texture and load/store operations can use theremaining capacity. Integration within the shared memory/L1 cache 570enables the shared memory/L1 cache 570 to function as a high-throughputconduit for streaming data while simultaneously providing high-bandwidthand low-latency access to frequently reused data.

When configured for general purpose parallel computation, a simplerconfiguration can be used compared with graphics processing.Specifically, the fixed function graphics processing units shown in FIG.2, are bypassed, creating a much simpler programming model. In thegeneral purpose parallel computation configuration, the workdistribution unit 325 assigns and distributes blocks of threads directlyto the DPCs 420. The threads in a block execute the same program, usinga unique thread ID in the calculation to ensure each thread generatesunique results, using the SM 440 to execute the program and performcalculations, shared memory/L1 cache 570 to communicate between threads,and the LSU 554 to read and write global memory through the sharedmemory/L1 cache 570 and the memory partition unit 380. When configuredfor general purpose parallel computation, the SM 440 can also writecommands that the scheduler unit 320 can use to launch new work on theDPCs 420.

The PPU 300 may be included in a desktop computer, a laptop computer, atablet computer, servers, supercomputers, a smart-phone (e.g., awireless, hand-held device), personal digital assistant (PDA), a digitalcamera, a vehicle, a head mounted display, a hand-held electronicdevice, and the like. In one embodiment, the PPU 300 is embodied on asingle semiconductor substrate. In another embodiment, the PPU 300 isincluded in a system-on-a-chip (SoC) along with one or more otherdevices such as additional PPUs 300, the memory 204, a reducedinstruction set computer (RISC) CPU, a memory management unit (MMU), adigital-to-analog converter (DAC), and the like.

In one embodiment, the PPU 300 may be included on a graphics card thatincludes one or more memory devices 304. The graphics card may beconfigured to interface with a PCIe slot on a motherboard of a desktopcomputer. In yet another embodiment, the PPU 300 may be an integratedgraphics processing unit (iGPU) or parallel processor included in thechipset of the motherboard.

Exemplary Computing System

Systems with multiple GPUs and CPUs are used in a variety of industriesas developers expose and leverage more parallelism in applications suchas artificial intelligence computing. High-performance GPU-acceleratedsystems with tens to many thousands of compute nodes are deployed indata centers, research facilities, and supercomputers to solve everlarger problems. As the number of processing devices within thehigh-performance systems increases, the communication and data transfermechanisms need to scale to support the increased.

FIG. 6 is a conceptual diagram of a processing system 500 implementedusing the PPU 300 of FIG. 2, in accordance with one embodiment. Theexemplary system 565 may be configured to implement the method 100 shownin FIG. 1. The processing system 500 includes a CPU 530, switch 510, andmultiple PPUs 300 each and respective memories 304. The NVLink 310provides a high-speed communication links between each of the PPUs 300.The switch 510 interfaces between the interconnect 302 and the CPU 530.The PPUs 300, memories 304, and NVLinks 310 may be situated on a singlesemiconductor platform to form a parallel processing module 525.

In the context of the present description, a single semiconductorplatform may refer to a sole unitary semiconductor-based integratedcircuit fabricated on a die or chip. It should be noted that the termsingle semiconductor platform may also refer to multi-chip modules withincreased connectivity which simulate on-chip operation and makesubstantial improvements over utilizing a conventional busimplementation. Of course, the various circuits or devices may also besituated separately or in various combinations of semiconductorplatforms per the desires of the user. Alternately, the parallelprocessing module 525 may be implemented as a circuit board substrateand each of the PPUs 300 and/or memories 304 may be packaged devices. Inone embodiment, the CPU 530, switch 510, and the parallel processingmodule 525 are situated on a single semiconductor platform.

In one embodiment, the signaling rate of each NVLink 310 is 20 to 25Gigabits/second and each PPU 300 includes six NVLink 310 interfaces (asshown in FIG. 6, five NVLink 310 interfaces are included for each PPU300). Each NVLink 310 provides a data transfer rate of 25Gigabytes/second in each direction, with six links providing 300Gigabytes/second. The NVLinks 310 can be used exclusively for PPU-to-PPUcommunication as shown in FIG. 6, or some combination of PPU-to-PPU andPPU-to-CPU, when the CPU 530 also includes one or more NVLink 310interfaces.

In one embodiment, the NVLink 310 allows direct load/store/atomic accessfrom the CPU 530 to each PPU's 300 memory 304. In one embodiment, theNVLink 310 supports coherency operations, allowing data read from thememories 304 to be stored in the cache hierarchy of the CPU 530,reducing cache access latency for the CPU 530. In one embodiment, theNVLink 310 includes support for Address Translation Services (ATS),allowing the PPU 300 to directly access page tables within the CPU 530.One or more of the NVLinks 310 may also be configured to operate in alow-power mode.

FIG. 7 illustrates an exemplary system 565 in which the variousarchitecture and/or functionality of the various previous embodimentsmay be implemented. The exemplary system 565 may be configured toimplement the method 100 shown in FIG. 1.

As shown, a system 565 is provided including at least one centralprocessing unit 530 that is connected to a communication bus 575. Thecommunication bus 575 may be implemented using any suitable protocol,such as PCI (Peripheral Component Interconnect), PCI-Express, AGP(Accelerated Graphics Port), HyperTransport, or any other bus orpoint-to-point communication protocol(s). The system 565 also includes amain memory 540. Control logic (software) and data are stored in themain memory 540 which may take the form of random access memory (RAM).

The system 565 also includes input devices 560, the parallel processingsystem 525, and display devices 545, i.e. a conventional CRT (cathoderay tube), LCD (liquid crystal display), LED (light emitting diode),plasma display or the like. User input may be received from the inputdevices 560, e.g., keyboard, mouse, touchpad, microphone, and the like.Each of the foregoing modules and/or devices may even be situated on asingle semiconductor platform to form the system 565. Alternately, thevarious modules may also be situated separately or in variouscombinations of semiconductor platforms per the desires of the user.

Further, the system 565 may be coupled to a network (e.g., atelecommunications network, local area network (LAN), wireless network,wide area network (WAN) such as the Internet, peer-to-peer network,cable network, or the like) through a network interface 535 forcommunication purposes.

The system 565 may also include a secondary storage (not shown). Thesecondary storage 610 includes, for example, a hard disk drive and/or aremovable storage drive, representing a floppy disk drive, a magnetictape drive, a compact disk drive, digital versatile disk (DVD) drive,recording device, universal serial bus (USB) flash memory. The removablestorage drive reads from and/or writes to a removable storage unit in awell-known manner.

Computer programs, or computer control logic algorithms, may be storedin the main memory 540 and/or the secondary storage. Such computerprograms, when executed, enable the system 565 to perform variousfunctions. The memory 540, the storage, and/or any other storage arepossible examples of computer-readable media.

The architecture and/or functionality of the various previous figuresmay be implemented in the context of a general computer system, acircuit board system, a game console system dedicated for entertainmentpurposes, an application-specific system, and/or any other desiredsystem. For example, the system 565 may take the form of a desktopcomputer, a laptop computer, a tablet computer, servers, supercomputers,a smart-phone (e.g., a wireless, hand-held device), personal digitalassistant (PDA), a digital camera, a vehicle, a head mounted display, ahand-held electronic device, a mobile phone device, a television,workstation, game consoles, embedded system, and/or any other type oflogic.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Thus, the breadth and scope of a preferred embodiment shouldnot be limited by any of the above-described exemplary embodiments, butshould be defined only in accordance with the following claims and theirequivalents.

Machine Learning

Deep neural networks (DNNs) developed on processors, such as the PPU 300have been used for diverse use cases, from self-driving cars to fasterdrug development, from automatic image captioning in online imagedatabases to smart real-time language translation in video chatapplications. Deep learning is a technique that models the neurallearning process of the human brain, continually learning, continuallygetting smarter, and delivering more accurate results more quickly overtime. A child is initially taught by an adult to correctly identify andclassify various shapes, eventually being able to identify shapeswithout any coaching. Similarly, a deep learning or neural learningsystem needs to be trained in object recognition and classification forit get smarter and more efficient at identifying basic objects, occludedobjects, etc., while also assigning context to objects.

At the simplest level, neurons in the human brain look at various inputsthat are received, importance levels are assigned to each of theseinputs, and output is passed on to other neurons to act upon. Anartificial neuron or perceptron is the most basic model of a neuralnetwork. In one example, a perceptron may receive one or more inputsthat represent various features of an object that the perceptron isbeing trained to recognize and classify, and each of these features isassigned a certain weight based on the importance of that feature indefining the shape of an object.

A deep neural network (DNN) model includes multiple layers of manyconnected perceptrons (e.g., nodes) that can be trained with enormousamounts of input data to quickly solve complex problems with highaccuracy. In one example, a first layer of the DLL model breaks down aninput image of an automobile into various sections and looks for basicpatterns such as lines and angles. The second layer assembles the linesto look for higher level patterns such as wheels, windshields, andmirrors. The next layer identifies the type of vehicle, and the finalfew layers generate a label for the input image, identifying the modelof a specific automobile brand.

Once the DNN is trained, the DNN can be deployed and used to identifyand classify objects or patterns in a process known as inference.Examples of inference (the process through which a DNN extracts usefulinformation from a given input) include identifying handwritten numberson checks deposited into ATM machines, identifying images of friends inphotos, delivering movie recommendations to over fifty million users,identifying and classifying different types of automobiles, pedestrians,and road hazards in driverless cars, or translating human speech inreal-time.

During training, data flows through the DNN in a forward propagationphase until a prediction is produced that indicates a labelcorresponding to the input. If the neural network does not correctlylabel the input, then errors between the correct label and the predictedlabel are analyzed, and the weights are adjusted for each feature duringa backward propagation phase until the DNN correctly labels the inputand other inputs in a training dataset. Training complex neural networksrequires massive amounts of parallel computing performance, includingfloating-point multiplications and additions that are supported by thePPU 300. Inferencing is less compute-intensive than training, being alatency-sensitive process where a trained neural network is applied tonew inputs it has not seen before to classify images, translate speech,and generally infer new information.

Neural networks rely heavily on matrix math operations, and complexmulti-layered networks require tremendous amounts of floating-pointperformance and bandwidth for both efficiency and speed. With thousandsof processing cores, optimized for matrix math operations, anddelivering tens to hundreds of TFLOPS of performance, the PPU 300 is acomputing platform capable of delivering performance required for deepneural network-based artificial intelligence and machine learningapplications.

FIG. 8 illustrates an exemplary system 800 for performing autonomouspath navigation using deep neural networks, according to one embodiment.As shown, the system 800 includes a camera module 802 in communicationwith a TrailNet DNN module 804, an object detection DNN module 806, andan obstacle detector module 808. In one embodiment, the camera module802 may provide visualization data (e.g., image data, radar data, depthdata, lidar data, infrared data, sonar data, etc.) to the TrailNet DNNmodule 804, the object detection DNN module 806, and the obstacledetector module 808. In another embodiment, the camera module may manageone or more cameras of a variety of different types within a vehicle.

Additionally, in one embodiment, the TrailNet DNN module 804 may receivevisualization data from the camera module 802, and may output vehiclelocation information. For example, the TrailNet DNN module 804 mayoutput three numbers that indicate the orientation of the vehicle withrespect to the path, and three numbers output by the DNN that indicatethe lateral position of the vehicle with respect to the path.

Further, in one embodiment, the object detection DNN module 806 mayreceive visualization data from the camera module 802, and may output anindication as to whether a person or large animal is present within thevisualization data (e.g., utilizing a DNN such as a YOLO DNN, etc.). Inanother embodiment, the obstacle detector module 808 may receivevisualization data from the camera module 802, and may output a set ofweights indicating a likelihood of obstacles at various locations anddistances (e.g., utilizing simultaneous location and mapping (SLAM),etc.). In this way, the obstacle detector module 808 may identify alocation of a camera within a scene, and may provide information about arelative location of static objects within the scene.

Further still, the system 800 includes a controller module 810. In oneembodiment, the controller module 810 may receive vehicle locationinformation from the TrailNet DNN module 804 (e.g., representing thevehicle's path orientation and lateral position), and may createsteering directions (e.g., a steering angle for the vehicle, etc.),utilizing the vehicle location information.

Also, the system 800 includes a communication module 812. Thecommunication module 812 may receive the steering directions in a firstformat (e.g., a ROS protocol, etc.) from the controller module 810, andmay convert then to messages in a second format (e.g., a MAV protocol,etc.). The communication module 812 may then broadcast the convertedmessages in the second format to a vehicle systems module 814, utilizinga communication protocol 816.

In addition, in one embodiment, the vehicle systems module 814 mayreceive the converted messages, and may use such messages to control oneor more physical components of the vehicle (e.g., in order to controlmovement of the vehicle, etc.). In this way, the controller module 810may compute steering directions and send the steering directions to thecommunication module 812, which may convert the directions to adifferent format and send them to the vehicle systems module 814 forimplementation at the vehicle.

Further, the system 800 includes a manual input device module 818. Themanual input device module 818 may receive input from a user (e.g., astartup indicator, a kill switch selection, a manual override selection,etc.), and may send such information to the controller module 810. Inthis way, manual user input may be provided to the system 800.

Further still, the camera module 802, the TrailNet DNN module 804, theobject detection DNN module 806, the obstacle detector module 808, thecontroller module, the communication module 812, and the manual inputdevice module 818 are all implemented within a single processor 820.Communication between such modules may be made using a predeterminedprotocol (e.g., a ROS protocol, etc.). The vehicle systems module 814 isimplemented within control hardware 822 of the vehicle that is separatefrom the processor 820.

Low-Flying Autonomous Mav Trail Navigation Using Deep Neural Networksfor Environmental Awareness Introduction

In one embodiment, autonomously following a man-made trail in the forestis a challenging problem for robotic systems. Applications for such acapability include, among others, search-and-rescue, environmentalmapping, wilderness monitoring, and personal videography. Micro aerialvehicles (MAVs) offer a number of advantages for solving this problem:they are not limited by the difficulty or traversability of the terrain,they are capable of high speeds, and they have the ability to quicklyswitch from one trail to another by flying through or over the forest.

In order for a complete MAV system to follow a trail, it may not onlydetect the trail in order to determine its steering commands, but italso may be aware of its surroundings. An MAV that lacks such acapability is in danger of colliding with overhanging branches or, evenworse, with people or pets using the trail. Environmental awareness istherefore one component for trail-following robots, particularly forlow-flying MAVs.

In one embodiment, a MAV system is provided for autonomous trailfollowing. The system may use a deep neural network (DNN) (calledTrailNet in this example) for determining the MAV's view orientation andlateral offset within the trail. The computed pose may then be used forcontinuous control to allow the MAV to fly over forest trails. Inaddition, vision modules for environmental awareness may enable the MAVto detect and avoid people and pets on the trail, as well as to estimatedepth in front of the robot for the purpose of reactively avoidingobstacles. All subsystems may run simultaneously in real time on boardthe MAV using a standalone computing device. On-board processing may beused to ensure the safety of this mission-critical system.

In one embodiment, a hardware/software system may be implemented forenvironmentally aware autonomous trail navigation using DNNs that mayrun in real time on board an MAV.

In another embodiment, a DNN architecture may be implemented for traildetection with improved accuracy and computational efficiency via a lessconfident classification scheme for more stable control as well asadditional categories for estimating both view orientation and lateraloffset.

In yet another embodiment, a methodology for retraining a DNN may beimplemented with 6 categories (for view orientation and lateral offset)by transfer learning from a network with 3 categories (orientationonly).

System Description

To ensure a robust and flexible platform for forest flight experiments,inexpensive off-the-shelf components may be used. One exemplary hardwaresetup may include a quadcopter or drone with autopilot software, anintegrated computing device, and a carrier board. The vision processingmay use a forward-facing camera. All processing may be done on theintegrated computing device.

The MAV may be equipped with a downward-facing, high framerate opticalflow sensor with sonar and lidar. Developed the flow sensor may providereliable metric position and attitude estimation by computing 2D opticalflow on the ground, then using ground distance measurements and gyroreadings to compute vehicle ground speed. Once computed, this speed maybe sent to an extended Kalman filter (EKF) running on flight controllerhardware to be fused with other sensor measurements (e.g., IU) for evenmore precise state estimation.

The diagram in FIG. 9 illustrates an exemplary software architecture900, according to one embodiment. A flight stack may be used as firmware902 for the flight controller hardware autopilot 922. The flightfirmware 902 may provide flexible and robust control over a range of MAVconfigurations. It may include software-in-the-loop (SITL) simulation,which may be used for controller testing and debugging. The on-boardcomputer may communicate with the flight firmware 902 via apredetermined protocol (e.g., MavLink, etc.). The Robotic OperatingSystem (ROS) 904 may be run on the on-board computer. As shown in FIG.9, the architecture 900 uses the following ROS nodes 906-910: a cameradriver node 906 for reading USB camera input, a joystick driver node 908for reading game controller commands used for teleoperation (e.g.,during training and for emergency override), and a messaging bridge toexternal autopilot module 910 for communicating with the flight firmware902.

In one embodiment, vision processing may be performed by three nodes912-916. A TrailNet DNN node 912 applies a trained TrailNet DNN. Anobject detection node 914 runs real-time object detection DNN. Anobstacle detector node 916 runs a visual odometry algorithm, whoseoutput may be converted to a camera-centric depth map for obstacledetection and avoidance.

The controller node 920 may be responsible for computing desiredmovement commands (waypoints) per current TrailNet DNN predictions,detected obstacles/objects and teleoperation commands. For safety, theteleoperation commands may take precedence over DNN predictions, so ahuman operator may override the MAV at any time to prevent undesirablemovements. The computed waypoint may then be sent to the messagingbridge to external autopilot module 910 which resubmits it to the flightfirmware 902 via a communication protocol 918. A right-handed ENU(east-north-up) inertial coordinate frame may be used for waypointcomputation, which may be converted to the flight firmware 902'sright-handed NED (north-east-down) coordinate frame.

Vision-Based Processing

This section describes the processing performed by the three nodes912-916 using a forward-facing camera.

Estimating Lateral Offset and View Orientation with DNN

FIG. 10 shows an exemplary TrailNet DNN node 1000 implementing a deepneural network (DNN) 1002 that is used for estimating the MAV's lateraloffset and view orientation with respect to the trail, according to oneembodiment. The DNN 1002 may include a ResNet-18 with one or morechanges (e.g., removed batch normalization, replaced ReLUs with shiftedReLU (SReLU), activation functions, which are computationally efficientapproximations to the highly effective exponential linear units (ELUs),a double-headed fully connected output layer, etc.).

In one embodiment, the TrailNet DNN architecture may be used todetermine the MAV's view orientation and lateral offset with respect tothe trail center. The network (labeled s-ResNet-18) may include aResNet-18 architecture, but without batch normalization and with ReLUreplaced by shifted ReLU. The first convolution layer may be 7×7,whereas all the others may be 3×3. Some layers may downsample usingstride of 2; all others may use a stride of 1. All weights except thelateral offset layer may be trained with the IDSIA trail dataset, afterwhich these weights may be frozen, and the lateral offset layer weightsmay be trained with a dataset. A final joint optimization step may alsobe performed.

In another embodiment, classification may be performed with soft labels,rather than regression, because of the ease of data collection andlabeling, as well as reduced sensitivity to noise. In one embodiment,the network may output 6 categories rather than 3 to capture not onlythe 3 orientations with respect to the trail (facing left/facingcenter/facing right) but also the 3 lateral offsets (shiftedleft/centered/shifted right) with respect to the trail center. Theseadditional categories may help provide more accurate state estimationand reliable trail following. With just 3 categories, if the MAV fliesclose to the trail edge but parallel to the trail, the DNN may not causeit to turn, because it is already oriented straight. Eventually, thisnegligence may cause it to hit tree branches near the edge. Thus, robustnavigation is precluded with just 3 categories, because of thedifficulty of resolving the ambiguity of needing to turn to correct anorientation error, and needing to fly in a non-straight path to correcta lateral offset error.

Training DNNs may requires large amounts of data. One exemplary approachto training the 6-category DNN applies principles of transfer learning.A 3-category DNN may be trained to predict view orientation(left/center/right), using a trail dataset. This dataset may includefootage of hikes recorded by 3 cameras (aimed left 30, straight, andright 30), with enough cross-seasonal and landscape variety to train allbut the lateral offset layers of the network.

To train the rest of the network, a dataset may be collected (e.g.,using a 3-camera rig), in which cameras are mounted on a bar (so thedistance between adjacent cameras was is a predetermined distance). Datamay be gathered over several trails by recording video footage of allcameras simultaneously as the cameras are moved along a middle of thetrail. The videos may be cropped (e.g., to 60 horizontal FOV, etc.) andmay be used to train the second 3-category head of the network used topredict lateral offset (left/center/right), while freezing all the otherweights.

In one embodiment, setting a predetermined baseline between cameras mayenable the network to disambiguate lateral offset from view orientation.

During training, a data augmentation pipeline may be used, including:random horizontal flips (with appropriate label changes); randomcontrast (e.g., 0.2 radius), brightness (e.g., 0.2 radius), saturation(e.g., 0.4 radius), sharpness (e.g., 0.3 radius) and jitter with randompermutations of these transformations; random scale jitter (e.g., min:0.9, max: 1.2); random rotations (e.g., max abs angle: 15); and randomcrops.

In another embodiment, one or more loss functions may be used. Forexample, the following loss function may be implemented during training:

$\begin{matrix}{\mathcal{L} = {\underset{\underset{{cross}{entropy}}{︸}}{- {\sum\limits_{i}{p_{i}\ln\left( y_{i} \right)}}} - \underset{\underset{{entropy}{reward}}{︸}}{\lambda_{1}\left( {- {\sum\limits_{i}{y_{i}\ln\left( y_{i} \right)}}} \right)} + \underset{\underset{penalty}{\underset{{side}{swap}}{︸}}}{\lambda_{2}\phi(y)}}} & (1)\end{matrix}$

where p_(i) and y_(i) are the smoothed ground truth label and networkprediction of category i∈{left, center, right}, respectively, y is a3-element vector containing all y_(i), λ1 and λ2 are scalar weights, andthe side swap penalty penalizes gross mistakes (i.e., swapping left andright):

$\begin{matrix}{{\phi(y)} = \left\{ \begin{matrix}{y_{left}} & {{{if}\hat{i}} = {right}} \\y_{right} & {{{if}\hat{i}} = {left}} \\{0} & {{{if}\hat{i}} = {center}}\end{matrix} \right.} & (2)\end{matrix}$

where î=arg max_(i) p_(i) is the ground truth category. This lossfunction may be used for training both the view orientation and lateraloffset heads of the network. Label smoothing in the first term and theentropy reward term together may help reduce overconfident behavior ofthe network, which may help enable stable flight.

Additionally, in one embodiment, a controller may be implemented to mixprobabilistic DNN predictions. This design may simplify transforming DNNpredictions into flight commands. Each time the TrailNet DNN sends itsprediction, the controller may compute a small counterclockwise turningangle α by:

α=β₁(y _(right) ^(vo) −y _(left) ^(vo)+β₂(y _(right) ^(lo) −y _(left)^(lo)),  (3)

which is the weighted sum of differences between the right and leftpredictions of the view orientation (vo) and lateral offset (lo) headsof the network, where β₁ and β₂ are scalar angle parameters that controlturning speed. We may set β₁=β₂=10°.

Once the turn angle is known, a new waypoint may be computed that islocated some distance in front of the MAV and at a turn angle relativeto MAV's body frame. The distance to the waypoint may affect thevehicle's speed. We set the orientation to face the new waypointdirection. The waypoint is converted to the inertial frame and sent(with a fixed distance to the ground) to the messaging bridge toexternal autopilot module for autopilot flight plan execution.

Object Detection with DNN

For safety, system collision avoidance may be implemented. An objectdetection DNN may be responsible for detecting objects, which may not bevisible to the obstacle detector module if they are independentlymoving. For each detected object, the network may provide bounding boximage coordinates. When the box size exceeds a threshold percentage ofthe image frame, the controls from Equation (3) may be overridden tocause the MAV to stop and hover.

One exemplary DNN that may be used for object detection is based on aYOLO DNN with modifications to allow efficient execution using anintegrated computing device. The network may be retrained on one or moredatasets.

Obstacle Detection and Avoidance with Monocular SLAM

In addition to higher-level navigation tasks such as trail following andsemantic object detection, an autonomous MAV may be able to quicklydetect and avoid obstacles in its path, even if these obstacles havenever been seen before (and are therefore not available for training).Such obstacles can be static, such as trees or walls, or dynamic, suchas people, animals, or moving vehicles. For safety reasons, the systemmay be robust in the presence of complex, highly dynamic environmentssuch as forest trails, and in the face of changes in lighting, shadows,and pose.

One approach to low-level obstacle detection may include stereo-basedmatching. Monocular techniques may also be used, includingdepth-from-single-image techniques using machine learning and deeplearning methods. Another technique may estimate depth using a monocularvideo stream.

In one embodiment, a direct sparse odometry (DSO) method may be used.For example, DSO may compute semi-dense 3D maps of the environment andmay be computationally efficient. The DSO method may be run on the ARMarchitecture of the integrated computing device. On this platform, theDSO may provide updates to the camera pose estimates as well as thedepth image, and may update its keyframes.

During flight, the DSO may provide an estimate of the camera's globalpose x_(dso) and an inverse depth image I_(dso). Using the rectifiedcamera intrinsics, I_(dso) may be converted into a 3D point cloud in thelocal space of the camera. To use these points for navigation orobstacle detection, they may be put in the MAV's frame of reference,including proper metric scale. This similarity transform may bedetermined using the odometry information provided by the MAV's othersensors.

Specifically, at any given time the optical flow sensor may be used togenerate an estimate of the current pose (xmav) of the vehicle in theinertial frame. When the visual odometry system provides an x_(dso),I_(dso) pair, it may be associated with the latest pose. Once several ofthese measurement pairs have been generated, Procrustes analysis may beused to generate the rigid similarity transformation between the MAV'sframe of reference and that of the visual odometry measurements. Thistransform may then be used to put the points extracted from I_(dso) intothe MAV's frame of reference, where nearby objects may then be detected.The set of measurement pairs (x_(dso) paired with x_(mav)) may beupdated when the MAV's motion generates sufficient parallax. These pairsmay be kept in a circular buffer, so eventually older measurements maybe discarded in favor of new ones. This moving window has the effect ofpotentially changing the metric scale over time, but more importantly itmay allow the system to be robust to measurement error and avoidpathological initializations.

CONCLUSION

An autonomous MAV system may be implemented that navigates forest trailsunder the canopy using deep neural networks (DNNs). A TrailNet DNN mayutilize shifted ReLU activation functions for increased accuracy andcomputational efficiency, and may incorporate 3 additional categoriesvia transfer learning to enable the estimation of both lateral offsetand view orientation with respect to the trail. The DNN may alsoimplement a loss function to prevent overconfidence in the network.Together, these improvements may yield smoother and more robustnavigation control. Environmental awareness may also be generated withadditional perceptual modules, including DNN-based object detection andobstacle detection via monocular visual odometry. All software may runsimultaneously in real time on an on-board computing device within theMAV. Together, these improvements may enable fully autonomous, saferobotic navigation in unstructured environments.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Thus, the breadth and scope of a preferred embodiment shouldnot be limited by any of the above-described exemplary embodiments, butshould be defined only in accordance with the following claims and theirequivalents.

What is claimed is:
 1. A method, comprising: calculating based, at leastin part, on one or more neural networks, a lateral position of a vehiclewith respect to a path.
 2. The method of claim 1, further comprising:using the lateral position to identify a location of the vehicle.
 3. Themethod of claim 2, further comprising: controlling the vehicle bypositioning the vehicle to the identified location based, at least inpart, on steering directions received from a controller, wherein thecontroller uses the lateral position to generate steering directions. 4.The method of claim 1, further comprising: receiving image data, inreal-time, from one or more imaging devices; and using the image data,at the one or more neural networks, to calculate the lateral position ofthe vehicle with respect to the path.
 5. The method of claim 1, whereinthe vehicle is an amphibious vehicle.
 6. The method of claim 1, whereinthe one or more neural networks comprise a deep neural network (DNN). 7.The method of claim 1, further comprising: sending image data, receivedat the vehicle, to a remote location; and obtaining, from the remotelocation using the one or more neural networks to process the imagedata, the lateral position of the vehicle with respect to the path. 8.The method of claim 7, wherein the one or more neural networks, at theremote location, further calculate a plurality of lateral offsets withrespect to a path center.
 9. A system, comprising: one or moreprocessors to train one or more neural networks to calculate a lateralposition of a vehicle with respect to a path.
 10. The system of claim 9,wherein the one or more processors are further to: train the one or moreneural networks using one or more received images; and wherein the oneor more received images comprise one or more labels indicating one ormore positions.
 11. The system of claim 9, wherein the one or moreprocessors are further to train the one or more neural networks toperform object detection based on the one or more received images. 12.The system of claim 10, wherein the one or more processors are furtherto send object data to a controller to calculate a size of an object inthe one or more received images.
 13. The system of claim 9, wherein theone or more processors are further to train the one or more neuralnetworks to perform obstacle detection based on the one or more receivedimages.
 14. A processor, comprising: one or more arithmetic logic units(ALUs) to calculate based, at least in part, on one or more neuralnetworks, a lateral position of a vehicle with respect to a path. 15.The processor of claim 14, wherein the one or more ALUs are further toobtain a command to adjust the vehicle to a location based on thecalculated lateral position.
 16. The processor of claim 15, wherein theone or more ALUs are further to: receive an image from one or moreinfrared imaging devices; and use information from the image tocalculate the lateral position of the vehicle with respect to the path.17. The processor of claim 14, wherein the lateral position of thevehicle with respect to the path comprises information indicating adirection the vehicle has shifted with respect to the path.
 18. Theprocessor of claim 14, wherein the calculated lateral position of thevehicle with respect to the path is represented numerically using atleast three numbers.
 19. The processor of claim 14, wherein the one ormore ALUs are further to: convert the lateral position of the vehicle,at a controller, to steering instructions; and send the steeringinstructions to vehicle.
 20. The processor of claim 19, wherein the oneor more ALUs are further to convert the steering instructions to a setof instructions executable by the vehicle.